In fact I could have already seen that as the site specifically mentions at the bottom of the page that there are hidden items because of tag filters, and there is no such thing visible in the video. Secondary option: does the 'number of items' selection switch back to 15 when you switch pages? That seems to have been reported before: New-Nav page size resets when changing list pages or tabs on a new or refreshed page
– GimbyFeb 8 '17 at 9:00